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Hip: J. M. Loughead, I. Starks, D. Chesney, J. N. S. Matthews, A. W. McCaskie, and J. P. Holland Removal of acetabular bone in resurfacing arthroplasty of the hip: A COMPARISON WITH HYBRID TOTAL HIP ARTHROPLASTY J Bone Joint Surg Br 2006; 88-B: 31-34 [Abstract] [Full text] [PDF]

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Authors' reply

James P Holland, Jonathan M. Loughead, and Andrew W. McCaskie   (12 June 2006)

Letter in response to 'Removal of acetabular bone in resurfacing arthroplasty of the hip'

Miss Sarah K Muirhead-Allwood, Mr Chirag Patel, Dr Prithvi Mohandas   (15 May 2006)

Removal of acetabular bone in resurfacing arthroplasty of the hip

Paul Roberts, Peter Grigoris   (6 April 2006)

Acetabular bone resection with total hip resurfacing needs further investigation

Pascal A. Vendittoli, Martin Lavigne, Alain G. Roy, Julien Girard   (31 March 2006)

Removal of acetabular bone in resurfacing arthroplasty of the hip

Robert F Spencer   (27 January 2006)

Femoral component sizing and its relationship to acetabular component size

Paul E. Beaulé   (18 January 2006)

Authors' reply 12 June 2006
James P Holland, Consultant in Trauma and Orthopaedics Department of Trauma and Orthopaedic Surgery Freeman Hospital, Newcastle upon Tyne, Jonathan M. Loughead, and Andrew W. McCaskie Send letter to journal: Re: Authors' reply Jim.Holland{at}nuth.nhs.uk James P Holland, et al.	Sir, We would like to thank Miss Muirhead-Allwood et al for their letter in response to our article. The views expressed in the letter are based on a personal and unpublished series. It does not follow the methods employed in our study and therefore direct comparison is impossible. If this were carried out, perhaps a more informed opinion could be given. The 'trade off' is between anatomically sizing the cup (which will equalise the size to that used in total hip replacement) and running the risk of notching for a matching head, or erring on the side of comfortable femoral fit. The latter technique in our series has given slightly larger cups in the larger-necked, bigger patient (smaller head/neck ratio) but in other patients has no observed effect. The aim of this paper was to highlight the issue for discussion and draw attention to the detail required for Birmingham hip replacement in certain patients with large broad femoral necks and relatively small heads (the 'pistol-grip' deformity). Certainly in most patients the size of cups is comparable, but it would be a shame if the drive to seat an anatomical cup was taken as paramount since it could lead to problems on the femoral side with impingement, an impairment of femoral head vascularity, a risk of notching in inexperienced hands and subsequent fracture, or the decision intra-operatively to opt for total hip replacement. This would not be good for what is emerging as the treatment of choice for younger, more active patients. J.P. Holland, Consultant in Trauma and Orthopaedics, J.M. Loughead, A.W. McCaskie, Freeman Hospital, Newcastle upon Tyne, UK.
Letter in response to 'Removal of acetabular bone in resurfacing arthroplasty of the hip' 15 May 2006
Miss Sarah K Muirhead-Allwood, Consultant Hip Surgeon The London Hip Unit, Mr Chirag Patel, Dr Prithvi Mohandas Send letter to journal: Re: Letter in response to 'Removal of acetabular bone in resurfacing arthroplasty of the hip' sma{at}londonhip.com Miss Sarah K Muirhead-Allwood, et al.	Sir, We read this paper with interest. Its demonstration that there is a greater loss of acetabular bone stock in resurfacing compared to conventional hip replacement, reminded me that at a revision hip meeting a decade ago I challenged Derek McMinn with the opinion that resurfacing was, in fact, not conservative on the acetabular side. Despite my initial belief that this was true, in the intervening years I have found that with careful femoral head preparation, it is possible to downsize the femoral head size sufficiently, without risk of neck notching, so that excess acetabular bone need not be removed. After seeing this paper, I have been prompted to look at the figures that I, as a single surgeon, have achieved. Out of 620 hip resurfacings, we have had one femoral neck fracture, and this was not actually associated with femoral neck notching, but with lack of full seating of the femoral component, and with the component being put in varus, thus increasing the offset. We have looked at our groups of hip resurfacing, and total hip replacement for the diagnosis of avascular necrosis and osteoarthritis, excluding development dysplasia of the hip, previous hip surgery, and patients with grossly abnormal femoral morphology, and studied the types of acetabular components used. Although this method has not used the contra-lateral hip as a reference, we would reasonably expect the average acetabular size for the natural acetabulum, for hip resurfacing and for Hybrid hip replacement, to be the same. In the group studied, we have used either a hemispherical Midland Medical Technology (MMT) hip resurfacing, or a hemispherical Trilogy uncemented socket. The sizes of these components, shown in the table below, are figures that, rather than supporting the figures of the study from the Freeman Hospital, if anything, show the opposite. We would refute, therefore, that the conclusion of this paper is correct, as with care and attention to detail, it is possible to safely use an acetabular component whose size is determined anatomically, rather than a larger shell to complement a reciprocal prosthesis. Comparison of acetabular component size for MMT and Trilogy prostheses in age-matched patients with osteoarthritis or avascular necrosis treated with arthroplasty between January 2002 and December 2005 During this period, I performed 337 male MMTs, with a mean age of 56.5 (26.6 to 75.5) and the mean acetabular size was 56.7 (50 to 64). I also performed 224 male Trilogy total hip replacements (THRs), with a mean age of 68.9 (49.4 to 75.5) and the mean acetabular size was 57.5 (50 to 70). With regard to the female patients, I performed 138 MMTs, with a mean age of 54.2 (28.3 to 70.5), and the mean acetabular size was 51.1 (46 to 58). This compares with 224 female Trilogy THRs, with a mean age of 65.5 (39.9 to 70.5), and the mean acetabular size was 53.5 (46 to 62). S.K. Muirhead-Allwood, Consultant Hip Surgeon, C. Patel, P. Mohandas, The London Hip Unit, UK.
Removal of acetabular bone in resurfacing arthroplasty of the hip 6 April 2006
Paul Roberts, Orthopaedic Surgeon Royal Gwent Hospital, Peter Grigoris Send letter to journal: Re: Removal of acetabular bone in resurfacing arthroplasty of the hip paulroberts{at}hipdoc.co.uk Paul Roberts, et al.	Sir, We read this article with interest. We fully agree with the authors that oversizing of the femoral component, which leads to oversizing of the acetabular component, must be avoided at the time of hip resurfacing. However, we believe it is misleading to imply that excessive acetabular removal of bone is a generic problem in a hip resurfacing procedure. The size of the components used is dependent not only on the morphology of the head/neck junction, but also on specific design features of the prosthesis, and on the surgical technique and philosophy with which it is implanted. Critical factors include the wall thickness of both components and the available size increments. These vary between different manufacturers.1 With respect to surgical technique, it is essential to be able to accurately and reproducibly prepare the femoral head to allow the use of the smallest possible femoral component without notching the femoral neck, particularly in cases with extensive neck re-modelling and/or osteophyte formation. This is facilitated by the use of sophisticated femoral instrumentation which allows accurate positioning of the cylinder cut, avoiding notching which may lead to a neck fracture post-operatively. If there is an extremely abnormal anatomy of the femoral head/neck junction, femoral and acetabular oversizing would be necessary, therefore it may be more appropriate to resect the femoral head and convert to a stemmed total hip replacement rather than sacrificing valuable acetabular bone stock. P. Roberts, Orthopaedic Surgeon, P. Grigoris, Royal Gwent Hospital, Newport, UK. 1. Grigoris P, Roberts P, Panousis K, Jin ZM. Hip resurfacing arthroplasty. The evolution of contemporary designs. Journal of Engineering in Medicine 2006; In Press.
Acetabular bone resection with total hip resurfacing needs further investigation 31 March 2006
Pascal A. Vendittoli, Assistant professor of surgery Hôpital Maisonneuve-Rosemont, Martin Lavigne, Alain G. Roy, Julien Girard Send letter to journal: Re: Acetabular bone resection with total hip resurfacing needs further investigation pa.vendittoli{at}videotron.ca Pascal A. Vendittoli, et al.	Sir, We read this article with interest. The authors conclude that more acetabular bone is removed during a surface replacement arthroplasty (SRA) than during a THA. The retrospective nature of the study and the patient selection for SRA, which includes more males with a different femoral pathoanatomy, may have biased their conclusion. To be able to compare the two groups, they used the femoral head diameter of the contra-lateral side for correction of size. This is not appropriate, as the contra-lateral side often has different pathoanatomy when compared to the operated side. Secondly, the limiting factor in hip resurfacing is the femoral neck diameter, not the femoral head diameter. We believe that 'resurfacing patients' are so different from 'standard THA patients' that a comparative study (the same surgeon operating on the patients during the same time period) is not accurate enough to address the question of bone resection adequately. In this study several factors may have influenced the amount of resection of acetabular bone, including the design of femoral and acetabular components and the increments of size of the implant system. When upsizing the femoral component, which may occur to avoid femoral neck notching, the larger the increment (4 mm for BHR), the more bone will be sacrificed on the acetabular side. The thickness of the acetabular component wall is important, since for a given femoral component size, the thicker the acetabular component, the more bone that needs to be removed. Surgical technique is also a major factor affecting the removal of bone. Successfully implanting a resurfacing implant is not simply an issue of obtaining fixation, good position and avoiding notching, surgeons rightly concerned about preserving femoral bone stock should also be concerned about preservation of acetabular bone stock. P.A. Vendittoli, Assistant Professor of Surgery, M. Lavigne, A.G. Roy, J. Girard, Hopital Maisonneuve-Rosemont, Canada.
Removal of acetabular bone in resurfacing arthroplasty of the hip 27 January 2006
Robert F Spencer, Consultant Orthopaedic Surgeon Weston General Hospital, Weston-super-Mare and Avon Orthopaedic Centre, Bristol Send letter to journal: Re: Removal of acetabular bone in resurfacing arthroplasty of the hip spencer{at}lrf.eclipse.co.uk Robert F Spencer	Sir, I read this article with interest. It confirms the widely-held impression that resurfacing hip arthroplasty may not be conservative in relation to acetabular bone when compared with hybrid hip replacement. The results coincide with similar evidence published elsewhere.1 Loughead et al recommend using the smallest femoral component compatible with the avoidance of femoral notching to minimise the extent of acetabular bone resection. Such narrow margins, if widely applied, may result in a certain number of cases of notching, with possible damage to the blood supply to the femoral head.2 Moreover, it has been suggested by Amstutz that small components in male patients may predispose to early revision.3 Too much emphasis may have been given to the issue of bone conservation on the acetabular side in hip resurfacing, and recent designs incorporating thinner (more conservative) acetabular shells have resulted in an increased number of early revisions.4 Accurate templating and selection of implants may be the most appropriate course to take. It should be remembered that revision of hip resurfacing more commonly involves the femoral side only, and patterns of osteolysis and further bone destruction are not comparable with those seen following the use of cementless acetabular components with polyethylene liners in hybrid hip arthroplasty. R.F. Spencer, MD,FRCS, Weston General Hospital, Weston-super-Mare, UK. 1. Crawford JR, Palmer SJ, Wimhurst JA, Villar RN. Bone loss at hip resurfacing: A comparison with total hip arthroplasty. Hip International 2005;15:195-8. 2. Beaule PE, Campbell PA, Hoke R, Dorey F. Notching of the femoral neck during resurfacing arthroplasty of the hip. J Bone Joint Surg [Br] 2006;88-B:35-9. 3. Amstutz HC, Beaule PE, Dorey FJ, et al. Metal-on-metal hybrid surface arthroplasty:Two to six-year follow-up study. J. Bone Joint Surg [Am] 2004;86-A:28-39. 4. Australian Orthopaedic Association National Joint Registry 2005.
Femoral component sizing and its relationship to acetabular component size 18 January 2006
Paul E. Beaulé, Orthopedic Surgeon University of Ottawa Send letter to journal: Re: Femoral component sizing and its relationship to acetabular component size pbeaule{at}ottawahospital.on.ca Paul E. Beaulé	Sir, I read this article with great interest, as the implantation of hip resurfacing represents a number of different technical challenges. An obvious one is appropriate implant sizing, permitting an appropriate press-fit of the acetabular component and avoiding damage of the femoral neck. In that respect, I believe that the conclusion of Loughhead and co-authors that more bone is removed from the acetabulum in hip resurfacing is somewhat misleading. First and foremost, the authors failed to mention that the resurfacing implant used in this study is available in 4 mm increments on the femoral side, however implants from at least two other major manufacturers are sized in 2 mm increments.1 Thus, at the time of femoral component preparation, if one tentatively prepares the head to size 50 mm, and the next size down is 46 mm and not 48 mm, then a 46 mm component may become too small for the femoral neck, forcing the surgeon to use the 50 mm-sized femoral component. Because of the necessary matching of the femoral and acetabular component in hip resurfacing, the femoral-component sizing has a direct impact on acetabular component size. In addition, a prospective randomised trial comparing hip resurfacing with standard total hip replacement has demonstrated no difference in acetabular component size.2 Finally, the authors did not comment on their technique of femoral-head sizing and preparation, in terms of removal or preservation of femoral head and neck osteophytes. If those osteophytes are not removed, the enlarged femoral head/neck junction will lead to the usage of a larger femoral component and subsequently a larger acetabular component.3 P.E. Beaulé,MD,FRCSC, Associate Professor University of Ottawa, Canada. 1. Grigoris P, Roberts P, Panousis K, Bosch H. The evolution of Hip Resurfacing Arthroplasty. Orthop Clin North Am 2005;36:125-34. 2. Lavigne M, Venditolli PA, Roy A. Prospective Randomized Clinical Trial comparing metal on metal total hip arthroplasty and hip resurfacing in patients less than 65 years old. Osteologie 2005;14 (Suppl.II):80-3.[abstract] 3. Beaule PE, Antoniades J. Patient Selection and Surgical Technique for Surface Arthroplasty of the Hip. Orthop Clin North Am 2005;36:177-85.